PROJECT ABSTRACT Although exposure to adversity in childhood and adolescence is an important predictor of subsequent physical and mental health, not enough is known about how adolescents respond to stressful and adverse environments and how they ?get under the skin? to influence health and development. Neighborhoods are one such important adolescent environment, as neighborhood disadvantage is associated with early emerging disparities in health and development that may set the stage for the accumulation of poor health and development over time. There are many important pathways by which neighborhoods may influence health over the life course, including health behaviors and challenging physical, social, and service environments. Perceiving neighborhoods as stressful may be one such mechanism by which neighborhood environments ?get under the skin? to influence health. Neighborhood environments may have both acute influences on stress-related processes, but also may have lifespan effects due to the chronic, cumulative effects of repeated exposures and the long-term toll of adapting to adverse neighborhood environments. Such adaptation may take the form of either habituation or sensitization to neighborhood-related stressors over time. However, assessing neighborhood influences on stress and emotion is methodologically challenging. There are no standardized neighborhood exposures that have been used to determine that exposure to neighborhood characteristics can elicit differences in stress and emotion. Moreover, while advancements in mobile technologies to measure functioning in context are important, in these studies exposures cannot be standardized and controlled, and testing chronic stress hypotheses would require extensive longitudinal measurement. Consequently, alternative design strategies are needed to clarify the role of stress in neighborhood effects. This study develops such a novel, alternative approach to address these issues by deploying a virtual reality (VR) based model of neighborhood disadvantage and affluence that creates an immersive experience approximating the experience of being in different neighborhoods. In this study, this model will be applied to understand neighborhood effects in a diverse sample of adolescents (n = 130) from a range of disadvantaged and affluent neighborhoods. The proposed study will employ a randomized experiment (n = 65 per condition), to determine (a) if virtual exposure to neighborhood disadvantage elicits differences in emotion and stress reactivity; (2) if growing up in a disadvantaged neighborhood results in habituation or sensitization to different neighborhood characteristics; and (3) if chronic stress results in habituation or sensitization to different neighborhood characteristics. This research will develop an innovative methodology that will help establish the role that neighborhoods may play in eliciting stress as well as the processes of adaptation to chronic stress and chronic neighborhood exposures. In addition, it will help establish a method that can be utilized more broadly to study contextual and social environmental influences on psychological and biological risk in adolescence.